Holography can be used to record (or store) a large amount of data and can also be used to record and reproduce, through exposure, interference fringes produced by superposition of a transmission wave or reflected wave from an object and a reference wave, or can be used to record and reproduce distribution of amplitude and a phase of turbulence of waves on a surface.
As a recording medium used for the holography, a mass producible dry type volume holographic recording medium has been used. As a raw material for use in this volume holographic recording medium, photopolymers, azobenzene-based or diarylethene-based photochromic materials, photorefractive materials such as LiNbO3 or liquid crystals have been known.
Among them, a volume holographic recording medium made of a photopolymer is excellent in industrial mass productivity and is a write-once read-only memory (WORM) which can be used for hologram optical disks or cards. For example, international publication No. WO2005/078532 discloses a volume hologram recording material comprising a polymer matrix having three-dimensional cross-linked structure, a polymerizable monomer and a tertiary amine compound as constituent components, wherein the polymer matrix is formed in the presence of the polymerizable monomer by a polymerization reaction different from the polymerization reaction of the polymerizable monomer.
To further increase the storage capacity of a volume holographic recording medium over those currently in use and to obtain a preformatable disk-like recording medium having low error rate, high sensitivity, high quality and high performance, a composition for a holographic recording medium, which can be made into a film having a uniform thickness and has photopolymer with an extremely low volume shrinking percentage when exposed to light, has been desired.